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Ataxia-telangiectasia is a syndrome of progressive cerebellar ataxia and other neurological manifestations associated with conjunctival and cutaneous telangiectases and with recurrent sino-pulmonary infections. Immunological and endocrine abnormalities occur. Two girls with this disease are described. The first had only minor respiratory infections; her serum proteins and immunity responses appeared normal. The second had recurrent pulmonary infections and bronchiectasis; she also exhibited sclerodermatous changes, poor development of secondary sexual characteristics with low urinary excretion of 17-ketosteroids, and lymphopenia. Autopsy at 17 years showed bilateral ovarian dysgerminomata and excessive cutaneous collagen as well as atrophy, and perhaps hypoplasia, of adrenals, thymus, spleen and lymphoid tissue (after steroid therapy). The cerebellum exhibited cortical degeneration. Both lungs were fibrotic with old and recent bronchopneumonia and bronchiectasis. The left lung was studied by injection of a latex preparation; no arteriovenous aneurysms were found, but the smaller pulmonary vessels showed some unusual morphological characteristics. 相似文献
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The progeny of one viviparous aptera from a strain of Myzus persicae which appeared to have become resistant to organophosphorus insecticides, were bred asexually in an environment free from these materials. At approximately the 7th generation, the clone when compared with a susceptible strain had a 25-fold resistance to demeton-methyl. With subsequent generations the resistance gradually declined and within 30 generations from its establishment the clone was no longer resistant.
Zusammenfassung Die Nachkommen einer viviparen Aptera von Myzus persicae, die offenbar resistent gegen organische Phosphorverbindungen geworden waren, wurden in einer insektizidfreien Umwelt geschlechtslos vermehrt. Ungefähr in der siebenten Generation, wenn der Klon mit einem normalen Stamm verglichen wurde, hatte er eine 25-fache Resistenz gegen Demeton-methyl. Mit weiteren Generationen nahm die Resistenz allmählich ab und 30 Generationen nach seiner Gründung war der Klon überhaupt nicht mehr resistent.相似文献
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Joseph B. Mazzola Alan W. Neebe Christopher V. R. Dunn 《Flexible Services and Manufacturing Journal》1989,1(2):115-142
Early flexible manufacturing system (FMS) production planning models exhibited a variety of planning objectives; typically, these objectives were independent of the overall production environment. More recently, some researchers have proposed hierarchical production planning and scheduling models for FMS. In this article, we examine production planning of FMS in a material requirements planning (MRP) environment. We propose a hierarchical structure that integrates FMS production planning into a closed-loop MRP system. This structure gives rise to the FMS/MRP rough-cut capacity planning (FMRCP) problem, the FMS/MRP grouping and loading (FMGL) problem, and the FMS/MRP detailed scheduling problem. We examine the FMRCP and FMGL problems in detail and present mathematical programming models for each of these problems. In particular, the FMRCP problem is modeled as a generalized assignment problem (GAP), and a GAP-based heuristic procedure is defined for the problem. We define a two-phase heuristic for the FMGL problem and present computational experience with both heuristics. The FMRCP heuristic is shown to solve problems that exhibit a dependent-demand relation within the FMS and with FMS capacity utilization as high as 99 percent. The FMGL heuristic requires very little CPU time and obtains solutions to the test problems that are on average within 1.5 percent of a theoretical lower bound. This FMS/MRP production planning framework, together with the resulting models, constitutes an important step in the integration of FMS technology with MRP production planning. The hierarchical planning mechanism directly provides for system-level MRP planning priorities to induce appropriate production planning and control objectives on the FMS while simultaneously allowing for necessary feedback from the FMS. Moreover, by demonstrating the tractability of the FMRCP and FMGL problems, this research establishes the necessary groundwork upon which to explore systemwide issues pertaining to the coordination of the hierarchical structure. 相似文献
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Burns A. R.; Hosford S. P.; Dunn L. A.; Walker D. C.; Hogg J. C. 《Journal of applied physiology》1989,66(5):2109-2116
The purpose of this study was to determine the pathology of cigarette smoke-increased permeability at the bronchioalveolar junction of the guinea pig. After exposure to either smoke or room air, guinea pigs were anesthetized and fluorescein isothiocyanate-dextran (FITC-D, mol wt 10,000) was aerosolized into their lungs. Blood samples taken through a carotid arterial cannula were analyzed by gel chromatography and spectrofluorometry for the presence of FITC-D. The results confirmed that, after smoke exposure, increased amounts of intact FITC-D molecules with a reported Einstein-Stokes radius of 22.2 A crossed the respiratory epithelium into the vascular space. Transmission electron-microscopic studies showed that the FITC-D diffused across damaged type I pneumocyte membranes and cytoplasm to reach the basal lamina and entered the alveolar capillaries through endothelial tight junctions. Damage to the alveolar epithelium was more frequent for the smoke-exposed animals than the room air-exposed animals (P less than 0.05). We conclude that smoke exposure damages type I cells and that inhaled FITC-D crosses the epithelial barrier at damaged type I cells of the bronchioloalveolar junctions. 相似文献
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Long-term in vitro function of adult hepatocytes in a collagen sandwich configuration. 总被引:12,自引:0,他引:12
In an effort to reconstruct the cellular polarity normally found in the liver, adult rat hepatocytes were sandwiched between two layers of hydrated rat tail tendon collagen matrix. Functionally, sandwiched hepatocytes maintained the secretion of albumin, transferrin, fibrinogen, bile acids, and urea for at least 6 weeks, whereas cells cultured on a single layer of collagen gel ceased such secretion in 1-2 weeks. After 1 week of culture on a single layer of collagen gel, hepatocytes could still recover these lost functions when a second layer of collagen gel was applied. The exact nature of the substrate for constructing the sandwich system appeared to be unimportant as long as it allowed cellular attachment. Hepatocytes cultured in the sandwich system appeared to maintain a distribution of actin filaments similar to the in vivo state, whereas cells cultured on a single layer of collagen gel showed abnormal formation of stress fibers. These studies suggest that simple manipulations of the configuration of extracellular elements can dramatically alter the behavior of cultured hepatocytes. 相似文献
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Summary A histochemical study was carried out on muscle fibre types in the myotomes of post-larval and adult stages of seven species of notothenioid fish. There was little interspecific variation in the distribution of muscle fibre types in post-larvae. Slow fibres (diameter range 15–60 m) which stained darkly for succinic dehydrogenase activity (SDHase) formed a superficial layer 1–2 fibres thick around the entire lateral surface of the trunk. In all species a narrow band of very small diameter fibres (diameter range 5–62 m), with only weak staining activity, occurred between the skin and slow fibre layer. These have the characteristics of tonic fibres found in other teleosts. The remainder of the myotome was composed of fast muscle fibres (diameter range 9–75 m), which stain weakly for SDHase, -glycerophosphate dehydrogenase, glycogen and lipid. Slow muscle fibres were only a minor component of the trunk muscles of adult stages of the pelagic species Champsocephalus gunnari and Pseudochaenichthys georgianus, consistent with a reliance on pectoral fin swimming during sustained activity. Of the other species examined only Psilodraco breviceps and Notothenia gibberifrons had more than a few percent of slow muscle in the trunk (20%–30% in posterior myotomes), suggesting a greater involvement of sub-carangiform swimming at cruising speeds. The ultrastructure of slow fibres from the pectoral fin adductor and myotomal muscles of a haemoglobinless (P. georgianus) and red-blooded species (P. breviceps), both active swimmers, were compared. Fibres contained loosely packed, and regularly shaped myofibrils numerous mitochondria, glycogen granules and occasional lipid droplets. Mitochondria occupied >50% of fibre volume in the haemoglobinless species P. georgianus, each myofibril was surrounded by one or more mitochondria with densely packed cristae. No significant differences, however, were found in mean diameter between fibres from red-blooded and haemoglobinless species. The activities of key enzymes of energy metabolism were determined in the slow (pectoral) and fast (myotomal) muscles of N. gibberifrons. In contrast to other demersal Antarctic fish examined, much higher glycolytic activities were found in fast muscle fibres, probably reflecting greater endurance during burst swimming. 相似文献